From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4A997C0044C for ; Sat, 3 Nov 2018 13:13:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 06AB420840 for ; Sat, 3 Nov 2018 13:13:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 06AB420840 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728684AbeKCWZF (ORCPT ); Sat, 3 Nov 2018 18:25:05 -0400 Received: from mail.kernel.org ([198.145.29.99]:49112 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727658AbeKCWZF (ORCPT ); Sat, 3 Nov 2018 18:25:05 -0400 Received: from vmware.local.home (cpe-66-24-56-78.stny.res.rr.com [66.24.56.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 93FC12082E; Sat, 3 Nov 2018 13:13:44 +0000 (UTC) Date: Sat, 3 Nov 2018 09:13:41 -0400 From: Steven Rostedt To: Masami Hiramatsu Cc: Josh Poimboeuf , Aleksa Sarai , "Naveen N. Rao" , Anil S Keshavamurthy , "David S. Miller" , Jonathan Corbet , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Shuah Khan , Alexei Starovoitov , Daniel Borkmann , Brendan Gregg , Christian Brauner , Aleksa Sarai , netdev@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH v3 1/2] kretprobe: produce sane stack traces Message-ID: <20181103091341.3d32683e@vmware.local.home> In-Reply-To: <20181103220012.55ecd97e671c43e4959c8b62@kernel.org> References: <20181101083551.3805-1-cyphar@cyphar.com> <20181101083551.3805-2-cyphar@cyphar.com> <20181101204720.6ed3fe37@vmware.local.home> <20181102050509.tw3dhvj5urudvtjl@yavin> <20181102065932.bdt4pubbrkvql4mp@yavin> <20181102091658.1bc979a4@gandalf.local.home> <20181102154325.bt6xoysl4xdl33wd@treble> <20181102121307.32e99414@gandalf.local.home> <20181103220012.55ecd97e671c43e4959c8b62@kernel.org> X-Mailer: Claws Mail 3.15.1 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 3 Nov 2018 22:00:12 +0900 Masami Hiramatsu wrote: > On Fri, 2 Nov 2018 12:13:07 -0400 > Steven Rostedt wrote: > > > Because that means if function graph tracer is active, then you can't > > do a kretprobe, and vice versa. I'd really like to have it working for > > multiple users, then we could trace different graph functions and store > > them in different buffers. It would also allow for perf to use function > > graph tracer too. > > Steve, how woul you allow multiple users on it? Something like this? > > ret_trampoline_multiple(){ > list_for_each(handler, &shadow_entry[i].handlers, list) > handler(shadow_entry[i]); > restore_retval_and_jump_to(shadow_entry[i].orig); > } > Something like that. But since it's not a single mapping between shadow entries and handlers, that is we have multiple tasks with multiple shadow entries and multiple handlers, we can't use a link list (two different parents per handler). I was thinking of a bitmask that represents the handlers, and use that to map which handler gets called for which shadow entry for a particular task. -- Steve From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Rostedt Subject: Re: [PATCH v3 1/2] kretprobe: produce sane stack traces Date: Sat, 3 Nov 2018 09:13:41 -0400 Message-ID: <20181103091341.3d32683e@vmware.local.home> References: <20181101083551.3805-1-cyphar@cyphar.com> <20181101083551.3805-2-cyphar@cyphar.com> <20181101204720.6ed3fe37@vmware.local.home> <20181102050509.tw3dhvj5urudvtjl@yavin> <20181102065932.bdt4pubbrkvql4mp@yavin> <20181102091658.1bc979a4@gandalf.local.home> <20181102154325.bt6xoysl4xdl33wd@treble> <20181102121307.32e99414@gandalf.local.home> <20181103220012.55ecd97e671c43e4959c8b62@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Josh Poimboeuf , Aleksa Sarai , "Naveen N. Rao" , Anil S Keshavamurthy , "David S. Miller" , Jonathan Corbet , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Shuah Khan , Alexei Starovoitov , Daniel Borkmann , Brendan Gregg , Christian Brauner , Aleksa Sarai , netdev@vger.kernel.org, linux-doc@vger.kerne To: Masami Hiramatsu Return-path: In-Reply-To: <20181103220012.55ecd97e671c43e4959c8b62@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Sat, 3 Nov 2018 22:00:12 +0900 Masami Hiramatsu wrote: > On Fri, 2 Nov 2018 12:13:07 -0400 > Steven Rostedt wrote: > > > Because that means if function graph tracer is active, then you can't > > do a kretprobe, and vice versa. I'd really like to have it working for > > multiple users, then we could trace different graph functions and store > > them in different buffers. It would also allow for perf to use function > > graph tracer too. > > Steve, how woul you allow multiple users on it? Something like this? > > ret_trampoline_multiple(){ > list_for_each(handler, &shadow_entry[i].handlers, list) > handler(shadow_entry[i]); > restore_retval_and_jump_to(shadow_entry[i].orig); > } > Something like that. But since it's not a single mapping between shadow entries and handlers, that is we have multiple tasks with multiple shadow entries and multiple handlers, we can't use a link list (two different parents per handler). I was thinking of a bitmask that represents the handlers, and use that to map which handler gets called for which shadow entry for a particular task. -- Steve From mboxrd@z Thu Jan 1 00:00:00 1970 From: rostedt at goodmis.org (Steven Rostedt) Date: Sat, 3 Nov 2018 09:13:41 -0400 Subject: [PATCH v3 1/2] kretprobe: produce sane stack traces In-Reply-To: <20181103220012.55ecd97e671c43e4959c8b62@kernel.org> References: <20181101083551.3805-1-cyphar@cyphar.com> <20181101083551.3805-2-cyphar@cyphar.com> <20181101204720.6ed3fe37@vmware.local.home> <20181102050509.tw3dhvj5urudvtjl@yavin> <20181102065932.bdt4pubbrkvql4mp@yavin> <20181102091658.1bc979a4@gandalf.local.home> <20181102154325.bt6xoysl4xdl33wd@treble> <20181102121307.32e99414@gandalf.local.home> <20181103220012.55ecd97e671c43e4959c8b62@kernel.org> Message-ID: <20181103091341.3d32683e@vmware.local.home> On Sat, 3 Nov 2018 22:00:12 +0900 Masami Hiramatsu wrote: > On Fri, 2 Nov 2018 12:13:07 -0400 > Steven Rostedt wrote: > > > Because that means if function graph tracer is active, then you can't > > do a kretprobe, and vice versa. I'd really like to have it working for > > multiple users, then we could trace different graph functions and store > > them in different buffers. It would also allow for perf to use function > > graph tracer too. > > Steve, how woul you allow multiple users on it? Something like this? > > ret_trampoline_multiple(){ > list_for_each(handler, &shadow_entry[i].handlers, list) > handler(shadow_entry[i]); > restore_retval_and_jump_to(shadow_entry[i].orig); > } > Something like that. But since it's not a single mapping between shadow entries and handlers, that is we have multiple tasks with multiple shadow entries and multiple handlers, we can't use a link list (two different parents per handler). I was thinking of a bitmask that represents the handlers, and use that to map which handler gets called for which shadow entry for a particular task. -- Steve From mboxrd@z Thu Jan 1 00:00:00 1970 From: rostedt@goodmis.org (Steven Rostedt) Date: Sat, 3 Nov 2018 09:13:41 -0400 Subject: [PATCH v3 1/2] kretprobe: produce sane stack traces In-Reply-To: <20181103220012.55ecd97e671c43e4959c8b62@kernel.org> References: <20181101083551.3805-1-cyphar@cyphar.com> <20181101083551.3805-2-cyphar@cyphar.com> <20181101204720.6ed3fe37@vmware.local.home> <20181102050509.tw3dhvj5urudvtjl@yavin> <20181102065932.bdt4pubbrkvql4mp@yavin> <20181102091658.1bc979a4@gandalf.local.home> <20181102154325.bt6xoysl4xdl33wd@treble> <20181102121307.32e99414@gandalf.local.home> <20181103220012.55ecd97e671c43e4959c8b62@kernel.org> Message-ID: <20181103091341.3d32683e@vmware.local.home> Content-Type: text/plain; charset="UTF-8" Message-ID: <20181103131341.vZ20tR66b7SnIHZDozdT77uqyZVHIBK7MdgwK4Pw2z8@z> On Sat, 3 Nov 2018 22:00:12 +0900 Masami Hiramatsu wrote: > On Fri, 2 Nov 2018 12:13:07 -0400 > Steven Rostedt wrote: > > > Because that means if function graph tracer is active, then you can't > > do a kretprobe, and vice versa. I'd really like to have it working for > > multiple users, then we could trace different graph functions and store > > them in different buffers. It would also allow for perf to use function > > graph tracer too. > > Steve, how woul you allow multiple users on it? Something like this? > > ret_trampoline_multiple(){ > list_for_each(handler, &shadow_entry[i].handlers, list) > handler(shadow_entry[i]); > restore_retval_and_jump_to(shadow_entry[i].orig); > } > Something like that. But since it's not a single mapping between shadow entries and handlers, that is we have multiple tasks with multiple shadow entries and multiple handlers, we can't use a link list (two different parents per handler). I was thinking of a bitmask that represents the handlers, and use that to map which handler gets called for which shadow entry for a particular task. -- Steve